The discovery of the crystalline structure was a giant step in the discovery of the tiny. René Just Haüy was one of the fathers of crystallography as a science and the discoverer that crystals can break into elementary geometric structures.
We have to clarify, because we have received some comment in this regard, that mineralogists distinguish two ways to break: fracture and exfoliate. In the video we don't make that distinction and we use breaking generically. Nor was Haüy using the hammer lightly. Why is this important? Because, for example, pyrite exfoliates into cubes (as mentioned in the video) but fractures irregularly (what in jargon is called conchoid fracture).
The videos of Histories of Science present brief and entertaining passages from our scientific and technological history. The videos, made for the Chair of Scientific Culture of the UPV / EHU are premiered in the science program Órbita Laika ( @orbitalaika_tve ), Mondays at 22:00 on RTVE 2 .